Gripping block arrangement and method of use

ABSTRACT

A gripping block includes a rear side with a largest rear side width, a front side with a smallest front side width and an outer surface with a friction generating surface arranged over at least a part of the outer surface, a first side face, and a second side face. The first side face and the second side face are arranged opposite of each other. The rear side abuts against an inner wall in a slot in a holding device. The largest rear side width is smaller than the smallest front side width.

CROSS REFERENCE TO PRIOR APPLICATIONS

This application is a U.S. National Phase application under 35 U.S.C. §371 of International Application No. PCT/NO2015/050123, filed on Jul. 3, 2015 and which claims benefit to Norwegian Patent Application No. 20140983, filed on Aug. 12, 2014. The International Application was published in English on Feb. 18, 2016 as WO 2016/024865 A1 under PCT Article 21(2).

FIELD

The present invention relates to a gripping block, a holding device for a gripping block, and a method for replacing a gripping block from the holding device. The present invention in particular applies to so-called “gripping tongs” or “gripping claws” used in connection with pipe handling. Such devices are in particular used to handle and/or to move pipes between different stations on a deck of a drilling vessel.

BACKGROUND

Prior art in other fields, in particular in connection with so-called “torque tongs”, “power tongs” and “iron roughnecks” used during assembly of drill pipe used in the drilling of wells for hydrocarbons (oil and gas), has described the use of such tongs to connect lengths of drill pipe together and/or to separate them. An upper pipe section is thereby generally rotated while a lower section of pipe/tubing is held in a fixed position. Gripping blocks provide sufficient friction against the pipe so that the pipe is held in the torque tong during connection with other pipe sections. The gripping blocks are therefore subjected to large forces and must be replaced regularly because of wear. An example of an iron roughneck comprising such gripping blocks is described in NO 319959 B1 in which a gripping block is mounted on each of three displaceable clamping devices. Each gripping block is equipped with a plurality of relatively sharp grooves which are clamped against the pipe and thereby grip the pipe.

NO 20092552 A describes a removable gripping block for torque tongs/power tongs. Disclosed is a holding device for a gripping block, wherein the holding device comprises a body comprising a longitudinal slot having internal walls to engage the corresponding surfaces on the gripper, wherein a first wall is movable between a retracted position in the slot, where the gripper is released, and a forward position the slot, where the gripper is clamped in abutment against the interior walls.

Known gripping blocks have been found to have a tendency of becoming stuck and to be difficult to replace when worn. The slot and the gripping block of the prior art must be designed with the least possible “play” or clearance between them to ensure that the gripping block is securely fixed in the slot. This is not necessarily compatible with the harsh environment in which the device operates, i.e., an environment with a high level of pollution from oil, dirt, dust, corrosion, etc., which can cause the small clearances in the slot to become clogged, thereby jamming the gripping block. This may result in the gripping blocks being stuck when they need to be replaced, resulting in extra time required for replacement, with the gripping blocks having to be hammered or knocked out, etc.

The design of traditional gripping blocks requires the gripping block holding device to have a matching, machined slot to hold the gripping block in place, resulting in the holding device being expensive to produce.

A need therefore exists for an improved holding device which promotes an easier exchange of gripping blocks, which remedies or reduces at least one of the disadvantages of the prior art.

SUMMARY

An aspect of the present invention is therefore to provide a gripping block and a holding device for a gripping block which saves time and which eases the work associated with the replacement of the gripping blocks.

In an embodiment, the present invention provides a gripping block which includes a rear side comprising a largest rear side width, a front side comprising a smallest front side width and an outer surface comprising a friction generating surface arranged over at least a part of the outer surface, a first side face, and a second side face. The first side face and the second side face are arranged opposite of each other. The rear side is configured to abut against an inner wall in a slot in a holding device. The largest rear side width is smaller than the smallest front side width.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in greater detail below on the basis of embodiments and of the drawings in which:

FIG. 1 shows an example of an arrangement of the gripping block and the holding device according to the present invention;

FIG. 2 shows a holding device and a gripping block according to the present invention, seen from the side and obliquely from above;

FIG. 3 shows a front view of the holding device and the gripping block of FIG. 2;

FIG. 4 shows a holding device and gripping block according to the present invention, seen from above;

FIG. 5 shows a sectional, side view through the center of the holding device with the gripping block;

FIG. 6 shows a gripping block of the present invention, seen from above;

FIG. 7 shows a front view of the gripping block of FIG. 6; and

FIG. 8 shows the gripping block of FIG. 6, seen from the side.

DETAILED DESCRIPTION

The present invention relates to a gripping block, such as a removable gripping block, which can be used in gripping claws, grip holders, torque tongs, power tongs, or any other device used for pipe handling offshore or on land. The present invention also relates to a holding device for a gripping block and to a method for replacing of a gripping block in a holding device.

In an embodiment, the present invention provides a gripping block comprising a rear side, a front side, and two opposite side faces, wherein at least a portion of the rear side is adapted to lie in abutment against an inner wall of a slot formed in a holding device for the gripping block, and wherein the front side of the gripping block is designed with a friction generating surface at least over a part of its outer surface, wherein the gripping block is further designed so that a largest width of the rear side has a shorter longitudinal extension than the smallest width of the front side of the gripping block.

The friction generating surface may be formed in the gripping block itself, such as serrations, grooves or an equivalent. The friction generating surface can also be attached to the gripping block front side in a suitable manner. This will be known to the skilled person and is therefore not further described herein.

In an embodiment of the present invention, at least one portion of the gripping block forward side can, for example, be formed convex relative to the gripping block rear side so as to provide a curved contact surface for the pipe to be gripped. The friction generating surface may then be formed in this convex area.

In order to keep the gripping block fixed in the holding device, the gripping block may be formed with an upper and lower flange, where each of the flanges may be provided as an extension of the gripping block rear side. One flange can then be designed to be placed in a recess in the holding device, while the other flange may be designed to form a construction for a locking member.

In an embodiment of the present invention, the gripping block can, for example, be designed so that the angle formed between each side face and the rear side of the gripping block is obtuse. It should be understood that the angle between each side face and the rear side of the gripping block may also be 90°, whereby each side face will then be arranged perpendicular to the rear side of the gripping block. An obtuse angle according to the present invention is defined to be an angle greater than 90° and less than 180°.

The present invention also provides a holding device for a gripping block, which holding device comprises a body which is formed with a slot, wherein the slot comprises an inner wall which is adapted to form an abutment against a rear side of the gripping block, when the gripping block is arranged in the holding device, and two opposite side surfaces, which side surfaces are arranged on either side of the inner wall, which side surfaces are shaped complementarily to the side faces of the gripping block, whereby each side surface and the inner wall may create an obtuse angle, or may be arranged perpendicular to each other. The holding device is further provided with a recess adapted for receiving a lower flange of the gripping block and a locking member for locking against an upper flange of the gripping block.

It should be understood that the holding device can also be formed with a recess adapted to receive an upper flange of the gripping block, whereby the locking member is then used to lock onto a lower flange of the gripping block.

The holding device may be further configured with a plurality of bores for receiving suitable fastening devices to attach the locking member. The holding device may also be formed with a plurality of bores to receive a suitable fastening device to attach the holding device to a torque tong or the like.

The bores used for the locking member and/or attachment of the holding device to a torque tong or the like can be formed as threaded holes, in which case the fastening device may be screws. A skilled person will understand, however, that the holes may be formed in other ways and that the fastening device can be bolts or similar, whereby this is not further described herein.

The present invention also provides a method for replacing a gripping block, where the method may include the steps of first loosening the attachment device from the locking part and removing the locking member from the holding device, so as to gain access to the gripping block. The gripping block is then removed from the slot, either being tilted out or lifted out of the recess. A new gripping block may then be inserted into the holding device. This is done by inserting the new gripping block in the slot and then sliding the gripping block downwards relative to the holding device so that the lower flange is pushed into the recess in the holding device, so as to prevent the gripping block from being taken out horizontally from the holding device. The locking member is then placed back over the gripping block upper flange, and the fastening device is used to attach the locking member to the holding device.

A non-limiting embodiment of the present invention is described below under reference to the drawings.

FIG. 1 shows a lifting arrangement 24, exemplified as an iron roughneck, with which a gripping block and a holding device for a gripping block according to the present invention may be used. The lifting arrangement 24 may comprise a number of arms with gripper claws in their outer ends, for lifting and/or handling of one or more pipes.

FIG. 2 shows a holding device 2 and a gripping block 1 according to the present invention, seen partly from the side and obliquely from above. The holding device 2 is, at least over a part of the holding device's 2 height, provided with a slot 4, which slot 4 comprises an inner wall 5 which engages a rear side 6 of the gripping block 1, as well as two opposing side surfaces 7, 8 arranged at each side of the inner wall 5, which side surfaces 7, 8 are complementarily shaped relative to side faces 9, 10 of the gripping block 1. Each of the side surfaces 7, 8 forms an obtuse angle θ₁ with the inner wall 5. The holding device 2 is further, towards its lower end, in the part of the holding device 2 which is not formed with the slot 4, formed with a recess 20 extending in the holding device's 2 longitudinal direction, to form an angled flange 16 for receiving a lower flange 12 of the gripping block 1.

When mounting the gripping block 1 in the holding device 2, the gripping block 1 is positioned into the slot 4 from above and is then pushed down in the holding device 2 so that a lower flange 12 of the gripping block 1 is received in the recess 20, until the angled flange 16 prevents a horizontal removal of the gripping block 1 from the recess 20. The gripping block 1 is then locked in the holding device 2 by placing an upper locking member 19 from above. The locking member 19 also is formed with an angled flange 16 which prevents both vertical and horizontal movement of the gripping block 1 in the slot 4. The locking member 19 is attached to the holding device 2 with suitable fasteners 17, 18, such as, for example, screws or bolts 17, 18, either from above (as shown in FIGS. 2-5) or perpendicular to the holding device 2. The locking member 19 locks the gripping block 1 in the slot 4 at the upper flange 13 of the gripping block 1 so that the rear side 6 of the gripping block 1 abuts against the inner wall 5, while the lower flange 12 of the gripping block 1 is disposed in recess 20 and kept in place via the angled flange 16.

FIG. 3 shows the holding device 2 and the gripping block 1 according to the present embodiment of the invention as seen straight from the front, while FIG. 4 shows the holding device 2 and the gripping block 1 as seen from above.

The holding device 2 may be formed with a fastening device 21 for attachment to a torque tong or the like, for example, through screws, bolts or an equivalent 21. The holding device 2 will then be formed with a plurality of bores 22. The holding device 2, or alternatively the gripping block 1, may alternatively be formed with one or more slots 4 or other suitable features (not shown in the drawings) to promote the manual removal of the gripping block 1 using, for example, a flat screwdriver, a crowbar or the like, to facilitate replacement of the gripping block 1.

FIG. 5 shows a sectional view through the center of the holding device 2 with gripping block 1 as seen from the side.

FIG. 6 shows a gripping block 1 according to the present invention as seen from above. The gripping block 1 has a rear side 6, a front side 11, and two opposing side faces 9, 10. The rear side 6 is adapted to abut against an inner wall 5 in a slot 4 in a holding device 2. The front side 11 is formed with a friction generating surface 15 over at least part of its outer surface. The friction generating surface 15 has a convex shape relative to the rear side 6 of the gripping block 1. This achieves the best possible grip around a pipe or tubular body which is held in, for example, a torque tong in which the holding device 2 is mounted.

As shown in FIG. 6, the rear side 6 has a shorter longitudinal extent than the front side 11 of the gripping block 1. This makes it easier to remove and insert the gripping block 1 in the holding device 2, since it is only the lower flange 12 and the upper flange 13 which holds the gripping block 1 in the slot 4, respectively via the angled flange 16, the holding device 2 and locking member 19. If the locking member 19 is released, only the recess 20, with the angled flange 16, will hold the gripping block 1 in the holding device 2.

The angle θ₁ between each of the two side faces 9, 10 and the rear side 6 is obtuse, i.e., θ₁>90°.

FIG. 7 shows the gripping block 1 according to the present invention as seen straight from the front.

The gripping block 1 is formed with a lower flange 12 and an upper flange 13. The lower flange 12 and the upper flange 13 are disposed in extension in opposite directions of the rear side 6 of the gripping block 1, respectively.

FIG. 8 shows the gripping block 1 according to the present invention as seen from the side.

The embodiment described herein and exemplified in the drawings enables an easier replacement of the gripping block 1 when it needs to be replaced and reduces the risk of the gripping block 1 jamming in the slot 4 of the holding device 2.

The embodiment described herein shall be deemed to be non-limiting. It is obvious that a skilled person may make modifications or alterations to the invention without departing from the invention as defined in the appended claims. Reference should also be had to the appended claims. 

What is claimed is: 1-8. (canceled) 9: A gripping block comprising: a rear side comprising a largest rear side width; a front side comprising a smallest front side width and an outer surface comprising a friction generating surface arranged over at least a part of the outer surface; a first side face; and a second side face, wherein, the first side face and the second side face are arranged opposite of each other, the rear side is configured to abut against an inner wall in a slot in a holding device, and the largest rear side width is smaller than the smallest front side width. 10: The gripping block as recited in claim 9, further comprising: a lower flange arranged to extend from the rear side; and an upper flange arranged to extend from the rear side; wherein the lower flange and the upper flange are arranged to extend in opposite directions from the rear side. 11: The gripping block as recited in claim 10, further comprising: at least two bores each of which is configured to receiving a fastening device. 12: The gripping block as recited in claim 9, wherein the friction generating surface is arranged to be convex relative to the rear side. 13: The gripping block as recited in claim 9, wherein, the first side face and the second side face are arranged so that an angle between the first side face and the rear side is the same as an angle between the second side face and the rear side; and each angle is obtuse. 14: A holding device for the gripping block as recited in claim 11, the holding device comprising: a slot comprising an inner wall which comprises a first side and a second side arranged opposite to the first side, the slot being arranged to abut against the rear side of the gripping block; a first side surface arranged on the first side of the inner wall; a second side surface arranged on the second side of the inner wall, a recess configured to receive the lower flange of the gripping block; and a separate locking member configured to lock against the upper flange of the gripping block; wherein, the first side surface and the second side surface are arranged complementary to the first side face and the second side face of the gripping block so that a respective obtuse angle is formed between the first side surface and the inner wall and between the second side surface and the inner wall. 15: The holding device as recited in claim 14, further comprising: at least two threaded boars each of which is configured to receive a fastening device for attachment of the separate locking member. 16: The holding device as recited in claim 15, wherein the separate locking member is configured to lock the upper flange so as to abut with the inner wall. 17: A method for a replacement of a first gripping block from a holding device with a second gripping block, the first gripping block and the second gripping block each comprising: a rear side comprising a largest rear side width, a front side comprising a smallest front side width and an outer surface comprising a friction generating surface arranged over at least a part of the outer surface, a first side face, a second side face arranged opposite of the first side face, a lower flange arranged to extend from the rear side, an upper flange arranged to extend from the rear side, the lower flange and the upper flange being arranged to extend in opposite directions from the rear side, and at least two bores each of which is configured to receiving a fastening device, wherein, the largest rear side width is smaller than the smallest front side width; the holding device comprising: a slot comprising an inner wall which comprises a first side and a second side arranged opposite to the first side, the slot being arranged to abut against the rear side of the gripping block, a first side surface arranged on the first side of the inner wall, a second side surface arranged on the second side of the inner wall, a recess configured to receive the lower flange of the gripping block, and a separate locking member configured to lock against the upper flange of the gripping block, wherein, the first side surface and the second side surface are arranged complementary to the first side face and the second side face of the gripping block so that a respective obtuse angle is formed between the first side surface and the inner wall and between the second side surface and the inner wall; the method comprising: loosening the fastening devices and removing the separate locking member to access the first gripping block; removing the first gripping block from the slot; inserting the second gripping block into the slot and the recess; and mounting the separate locking member with the fastening devices. 